Conventionally, a traffic signal control method (time-controlled pattern selection scheme) has been known in which a plurality of signal control parameters are stored for each time zone and the stored signal control parameters are selected in accordance with the time of day to perform traffic signal control. In this method, a traffic demand is obtained in advance for each time zone before the start of operation, the demands are formed into patterns by time of day, and signal control parameters suitable for each demand pattern are stored.
A traffic signal control method (pattern selection scheme based on the travel time) has also been proposed (see PTL 1) in which traffic conditions are obtained on the basis of a travel time acquired from a vehicle detector or from probe information or the like and thereafter stored signal control parameters are selected in accordance with the pattern of the obtained traffic conditions to perform traffic signal control. The term “probe information” is called floating car data (FCD) generally.
The above pattern-selection traffic signal control methods can be more easily introduced than a scheme for sequentially calculating signal control parameters in accordance with the traffic volume or congestion length, and only operate with one of a plurality of stored patterns. Therefore, the above traffic signal control methods have an advantage in that there is no concern of the above traffic signal control methods being out of expectation, unlike the case of sequential calculation.